Academy of Natural Sciences Scan Reveals the Bones of Satan…Fish

November 08, 2017

In “The Usual Suspects,” a character deadpans, “The greatest trick the devil ever pulled was convincing the world he didn’t exist.”

Although that line is used in the movie as a trick on the viewers, it may actually have some real-world implications for a species of blind, underground catfish that were officially named “Satan” more than half a century ago.

Satan eurystomus was given its unique moniker in 1947 because it has been only found to live deep below the surface (a la hell). There have been only a handful of specimens collected, and the last living ones were found in the 1980s. But a team from the Academy of Natural Sciences of Drexel University’s Ichthyology Department along with a researcher at the University of Texas, Austin, recently took part in full-body 3-D X-ray scans of some of the specimens that were found. Taking these scans means they can be compared to other catfish that Satan is thought to be related to.

The holotype of the Satan eurystomus from 1947. Courtesy of the University of Michigan.

“This fish has not been collected in more than 30 years and there are only 14 specimens in collections, making it really difficult to understand to what species they’re related,” said Mariangeles Arce H., PhD, collection manager in Ichthyology at the Academy.

A denizen of caves deep beneath Texas, Satan eurystomus (whose common name — Widemouth Blindcat — is decidedly less provocative) features pink-to-translucent skin and no eyes. Flat-headed, its wide mouth suggests that it feeds via suction on relatively large, whole prey, like the other catfish it might be related to.

Although the study’s scans provided a wealth of information and a much clearer picture of the fish, there’s still a host of discoveries to be made.

“Within the ictaluridae family — North American freshwater catfishes — there are a total of 4 known subterranean species,” Arce said. “We don’t have a “final” say on the relations since there is still some missing information in the other subterranean species. So our paper opens the door for more studies and is trying to understand the evolution of these blind catfishes.”

“Texas and Mexican blindcats are of special interest to biologists who seek to understand their origins, natural history and conservation status,” Lundberg explained. “How and when did their surface-dwelling ancestors enter subterranean waters and adapt to survive in total darkness with greatly reduced resources? The scientific approach to unraveling the origins of these so-called stygobitic (groundwater-adapted, from the Greek for Styx) species is to discover genetically-based characteristics that are shared by common ancestry with surface-living (epigean) relatives."